The invention relates generally to a method of converting the configuration of a transmission pump into a later model year configuration transmission pump assembly. More specifically the invention relates to a method of converting a 1984-1994 General Motors 700 R4 transmission pump assembly into a 1995 or later configuration General Motors transmission pump assembly allowing a low cost replacement transmission pump.
An automotive transmission multiplies engine torque or reduces engine rpm to match varying operating conditions in a manner optimizing engine power and torque. An automatic transmission generally comprises a torque converter, automatic transmission shafts, planetary gearsets providing different gear ratios, planetary holding members or clutches, transmission fluid pump, transmission shafts, hydraulic valves, shift linkage, converter housing, transmission case, transmission fluid pan, and an extension housing.
The automatic transmission is generally operated by a hydraulic fluid circuit. Pressure is developed by the transmission fluid pump, sometimes called an oil pump or front pump. The pump draws fluid from the transmission fluid pan and creates hydraulic pressure, which is then directed to other parts of the transmission to fill the torque converter, operate the holding member band and clutch assemblies, control shifting, lubricate the moving parts of the transmission, and circulate the fluid to and from an oil cooler for heat transfer. The pump is driven by the engine typically through driving lugs on the torque converter. When the engine is running, the pump produces power to operate the hydraulic system.
General Motors introduced a second generation transmission pump on its model 700 R4 transmission assembly in model year 1984 that remained basically unchanged through model year 1994. The 700 R4, (also designated 4L60E) utilizes a C-Vane type transmission oil pump comprising a pump body, a pump vane assembly, and a pump cover assembly. The 700 R4 transmission has been modified several times over the years. Some of these changes directly affected the compatibility of the transmission pumps between different model years.
When a transmission pump fails and needs to be replaced, the vehicle owner typically has a new or remanufactured transmission pump installed. New transmission pumps direct from the original equipment manufacturer (OEM) can be quite expensive. Significant cost savings can be obtained by using a remanufactured part. For example, a salvaged and remanufactured transmission pump from a 1984 model year 700-R4 transmission could be used for the same transmission for 1984-1994 model years. As these are older cars and cover over ten years of production, the number of salvageable transmission pumps are plentiful and comparatively low cost. However due to later model year changes in the transmission, the same pump could not be used for the same transmission of a 1995 model year. The limited number of salvaged transmission pumps from a transmission pump having a run of one or two years makes it virtually impossible to get a remanufactured part, thereby forcing the consumer to pay for a new OEM transmission pump.
Therefore, there remains a need in the art for a method of converting an older version of the transmission pump into a configuration compatible with later model year transmission pumps.
An object of the present invention is to provide an inexpensive and easily produced method for refurbishing transmission pump assemblies for later model year transmissions. These and other advantages are provided by a method of changing the configuration of a transmission pump assembly from a first configuration to a second configuration, the method comprising the following steps: a) providing a first configuration transmission pump assembly comprising a pump body and a pump cover, wherein the pump body and the pump cover each have a plurality of fluid passageways formed between worm tracks on at least one side thereof; b) removing a portion of the worm tracks from both the pump body and the pump cover; c) providing at least one insert; d) attaching the at least one insert into a predetermined position; and e) machining the pump cover and pump body to the second configuration.